The use of transfected fibroblasts and transgenic mice establishes that stimulation of T cells by the Mycoplasma arthritidis mitogen is mediated by E alpha.
Mycoplasma arthritidis produces a soluble protein which is active for murine and human lymphocytes when presented by Ia-bearing accessory cells. By using fibroblasts transfected in vitro with various class II Ag, we demonstrated that presentation of the M. arthritidis mitogen (MAM) to T cells was mediated by E alpha-containing molecules. We also showed that splenocytes from transgenic mice expressing E alpha heterozygously (B10.TRG E alpha+) or homozygously (B10.E alpha TG +/+) underwent a similar proliferation in response to MAM as compared with the failure of control B10.TRG E alpha- splenocytes to respond to MAM. Although splenocytes from inbred C3H and CBA mice exhibited much higher proliferative responses to MAM than did those from B10.TRG.E alpha+ or B10.E alpha TG +/+ mice, flow cytometry showed similar levels of E alpha expression. Furthermore, gamma-irradiated splenocytes from B10.TRG E alpha + mice presented MAM to T hybridoma cells with a similar efficacy as did splenocytes from C3H mice. The lesser response to MAM of lymphocytes from the E alpha transgenic mice as compared with those from C3H and B10.K mice was likewise not due to differential expression of their V beta TCR. We conclude that presentation of MAM to T cells is accomplished by E alpha-containing molecules. The studies also suggest that the conserved, nonpolymorphic regions of class II molecules may play an important role in host immune response to microbial products.
Cole
B C
BC
Department of Internal Medicine, University of Utah College of Medicine, Salt Lake City 84132.
David
C S
CS
Lynch
D H
DH
Kartchner
D R
DR
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D000941:Antigens; D000942:Antigens, Bacterial; D005347:Fibroblasts; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D008934:Mitogens / Q000276:immunology*; D009174:Mycoplasma / Q000276:immunology*; D011506:Proteins; D018089:Superantigens; D013601:T-Lymphocytes / Q000276:immunology*; D014162:Transfection
D000941:Antigens; D000942:Antigens, Bacterial; D000949:Histocompatibility Antigens Class II; D008934:Mitogens; C052996:Mycoplasma arthritidis mitogen; D011506:Proteins; D018089:Superantigens